Infants can have their thyroid function checked by blood collection through a vein, which is a routine test after birth to determine if there are any abnormalities in thyroid function. The method of checking thyroid function in infants is similar to that of adults, which is done through the method of blood collection from veins. The doctor will tie the proximal end of the vein with an elastic rubber band to make the vein congested with blood, and then use a thin needle to inject into the vein, and then use the method of negative pressure suction to collect blood for checking the thyroid function. Generally speaking, infants need to undergo this test routinely after birth to determine whether there is any abnormality of the function of thyroid glands. If an infant develops uncomfortable symptoms after the thyroid function check, it is recommended that he or she consult a doctor in time for standardized treatment under the doctor’s guidance. In addition, it is recommended to conduct the relevant examinations after birth under the guidance of the doctor and actively cooperate with the doctor to ensure the health of the child.